Biophysically-based computational models of nerve fibers are important tools for designing electrical stimulation therapies, investigating drugs that affect ion channels, and studying diseases that affect neurons. Although peripheral nerves are primarily composed of unmyelinated axons (i.e., C-fibers), most modeling efforts focused on myelinated axons. We implemented the single-compartment model of vagal afferents from Schild et al. 1994 and extended the model into a multi-compartment axon, presenting the first cable model of a C-fiber vagal afferent. We also implemented the updated parameters from Schild and Kunze 1997. We compared the responses of these novel models to three published models of unmyelinated axons (Rattay and Aberham 1993; Sundt et al. 2015; Tigerholm et al. 2014) and to experimental data from single fiber recordings. Comparing Schild et al. 1994 and 1997 revealed that differences in rest potential and action potential shape were driven by changes in maximum conductances rather than changes in sodium channel dynamics. Comparing the five model axons, the conduction speeds and strength-duration responses were largely within expected ranges, but none of the models captured the experimental threshold recovery cycle-including a complete absence of late subnormality in the models-and their action potential shapes varied dramatically. The Tigerholm et al. 2014 model best reproduced the experimental data, but these modeling efforts make clear that additional data are needed to parameterize and validate future models of autonomic C-fibers.

中文翻译：

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无髓鞘外周轴突计算模型的激发特性


基于生物物理的神经纤维计算模型是设计电刺激疗法、研究影响离子通道的药物以及研究影响神经元的疾病的重要工具。尽管周围神经主要由无髓鞘轴突（即 C 纤维）组成，但大多数建模工作都集中在有髓鞘轴突上。我们实施了 Schild 等人的迷走神经传入的单室模型。 1994 年，将该模型扩展为多室轴突，提出了第一个 C 纤维迷走神经传入的电缆模型。我们还实现了 Schild 和 Kunze 1997 的更新参数。我们将这些新颖模型的响应与三个已发表的无髓鞘轴突模型（Rattay 和 Aberham 1993；Sundt 等人 2015；Tigerholm 等人 2014）以及实验数据进行了比较单光纤录音。比较 Schild 等人。 1994年和1997年揭示，静息电位和动作电位形状的差异是由最大电导的变化而不是钠通道动力学的变化驱动的。比较五个模型轴突，传导速度和强度持续时间响应很大程度上在预期范围内，但没有一个模型捕获实验阈值恢复周期（包括模型中完全不存在晚期亚正常），并且它们的动作电位形状变化很大。泰格霍姆等人。 2014 年模型最好地再现了实验数据，但这些建模工作清楚地表明，需要额外的数据来参数化和验证自主 C 纤维的未来模型。